1. Field of the Invention
The present invention relates to a plasma process system and a plasma process method which perform processes, such as film deposition and etching, using a plasma.
2. Description of Related Art
A plasma process system which processes the surface of a substrate, such as a semiconductor wafer, using a plasma is used in a fabrication process for a liquid crystal display or the like. As plasma process systems, there are, for example, a plasma etching system which performs etching on a substrate and a plasma CVD system which performs chemical vapor deposition (Chemical Vapor Deposition: CVD). Of them, a parallel plate plasma process system is widely used because it has an excellent process uniformity and its system structure is relatively simple.
A parallel plate plasma process system has two parallel plate electrodes faces each other vertically in parallel to each other. A substrate is mounted on a lower electrode of the two electrodes. The upper electrode has an electrode plate facing the lower electrode and having multiple gas holes, and has a so-called shower head structure. The upper electrode is connected to a supply source for a process gas so that at the time of processing, the process gas is supplied between two electrodes through the gas holes in the electrode plate. The process gas supplied between the electrodes is turned into a plasma by the application of high-frequency power to the electrodes, and the surface of the substrate is processed by the plasma.
For the plasma process system to process the substrate surface with high uniformity, it is important to control the supply of the process gas from the individual gas holes with a high accuracy. In case where gas supply from the gas holes is not uniform, for example, the film thickness distribution on the substrate surface undergone film deposition becomes uneven.
The upper electrode of the shower head structure has a hollow diffusion portion inside. The diffusion portion is provided in such a way as to cover one side of the electrode plate and the process gas is diffused into multiple gas holes by the diffusion portion. To control the supply of the process gas from the gas holes in this structure, it is important to lead the gas to the gas holes by controlling the diffusion of the process gas at the diffusion portion.
To control the diffusion of the process gas at the diffusion portion, for example, a structure which separates the diffusion portion 21 into a plurality of areas and supplies the process gas to the individual areas has been developed. According to this structure, it is possible to control the amount of the process gas to be ejected from the gas holes that communicate with the individual areas by adjusting the amount of the process gas to be supplied to the individual areas. Accordingly, a process with high uniformity can be performed on the substrate surface.
In case where the structure is used, however, pipes respectively connected to a plurality of diffusion areas are required This increases the number of parts of the system, complicating the system structure, increasing the manufacturing cost and lowering the maintenanceability, such as maintenance. As apparent from the above, there have been no plasma process systems that could perform a process with high uniformity on the substrate surface.